1. Field of the Invention
The present invention relates to a rechargeable battery, and more particularly, to a rechargeable battery that is improved in its heat dissipation efficiency and a battery module having such rechargeable batteries.
2. Description of the Related Art
Unlike a primary battery, a rechargeable battery may be recharged. Low capacity batteries are used for various portable electronic devices such as phones, laptop computers, and camcorders. High capacity batteries are used as the power source for driving motors, such as those for hybrid electric vehicles (HEV).
Depending on their external shape, rechargeable batteries may be classified into different types, for example, prismatic and cylindrical batteries.
The high capacity rechargeable battery (hereinafter, referred as “battery module”) are composed of a plurality of rechargeable batteries (hereinafter, each referred as “unit battery”) so that it can be used to drive motors of machines requiring a high power source such as hybrid electric vehicles. The unit battery includes an electrode assembly having positive and negative electrodes and a separator interposed between the positive and negative electrodes, a case for receiving the electrode assembly, a cap assembly for sealing the case, and positive and negative terminals extending from the cap assembly and electrically connected to the positive and negative electrodes, respectively.
Conductive lead terminals are attached to the respective positive and negative electrodes to collect current and induce the collected current to the positive and negative terminals.
If the unit batteries are prismatic type batteries, the unit batteries are arranged such that the positive and negative terminals of one unit battery alternate with the positive and negative terminals of an adjacent unit battery. The adjacent positive and negative terminals of the adjacent unit batteries are electrically interconnected by conductive members to form the battery module.
The unit battery generates heat during the charge/discharge operation. The heat is generally dissipated to an external side through the case. The heat dissipation property of the unit battery is a very important factor on which the performance of the battery module depends.
When the heat dissipation is not properly realized, an internal temperature of the unit battery increases to deteriorate the performance of the unit battery. Sometime, the increased internal temperature may cause an explosion of the unit battery.
Since the battery module is comprised of several to tens of unit batteries connected in series or parallel, the reaction heat generated from the unit batteries must be more efficiently dissipated.
That is, if heat dissipation of the unit batteries is not properly realized, the internal temperature of the battery module may increase excessively. Accordingly, both the battery module and the device powered by the battery module may malfunction.
Particularly, when the battery module is used as the high capacity rechargeable battery for driving motors of the HEV, the heat dissipation property of the unit battery is of significant importance. That is, since the charge/discharge operation of the battery module is done with a large capacity of current, the internal temperature of the battery module increases excessively. This deteriorates the inherent performance of the battery module.
In addition, internal pressure of the unit battery increases due to internal chemical reaction of the unit battery. The increased internal pressure may deform a shape of the battery unit. This may causes deterioration of the battery performance. For the prismatic battery having a relatively high aspect ratio, such problems become more severe.
To solve the problems, a plurality of barriers are disposed between the unit batteries to provide channels between the unit batteries. As cooling air passes through the channels, the heat generated from the unit batteries is dissipated. However, this structure cannot yet sufficiently dissipate the heat out of the battery module. Furthermore, the battery shape deformation problem caused by the internal chemical reaction is not still solved.